Glycerol plasticised chitosan: A study of biodegradation via carbon dioxide evolution and nuclear magnetic resonance

The biodegradation of neat chitosan, glycerol plasticised chitosan films and their corresponding clay-based nano-biocomposites has been studied in simulated aerobic soil and composting environments using a respirometric method. The rate of biodegradation was much faster in soil and all test samples achieved close to 100% biodegradation within 70 days. During biodegradation under aerobic composting conditions the neat chitosan samples achieved approx 65% biodegradation and the plasticised chitosan samples achieved >85% biodegradation within 180 days. Additionally, nano-clay additives had no significant effect on the overall biodegradability of the chitosan-based materials during composting. High-resolution solid-state NMR studies were performed to examine the chemical structures of the plasticized chitosan and their nano-biocomposites. NMR studies indicated that the glycerol plasticizer was extracted into wet compost within first few days while acetic acid remained through strong hydrogen bonding with chitosan during the degradation process. Crown